Taiwan Trouble

I don't see how the U.S. will defend Taiwan when a solid chunk of the country wants to reunite with China in some way. I do not see the DPP sacrificing the amount of blood that would be necessary to win since it could descend into an all out civil war. Whereas I suspect both the Chinese army and the KMT would be willing to spill as much blood as possible to win, even if it means depopulating Taiwan.